1. Field of the Invention
This invention relates to a new and improved isolation liquid layer retention device which is particularly adapted for use with aqueous sample and reagent liquid containers in automated sample liquid analysis systems which utilize the isolation liquid to minimize sample liquid carryover thereby optimizing the accuracy of the sample liquid analysis results. 2. Description of the Prior Art
U.S. Pat. No. 4,515,753 issued May 7, 1985 to John L. Smith, et al for Integral Reagent Dispenser and assigned to the assignee hereof discloses, in FIGS. 8, 9 and 10, an isolation liquid lens yoke 290 comprising an isolation liquid lens loop 292 which floats upon the surface of an aqueous reagent liquid in a reagent liquid dispenser well, and which functions to centrally position a lens of an immiscible isolation liquid upon the surface of said reagent liquid for aspiration therefrom by an aspiration probe attendant reagent liquid aspiration. This lens loop comprises a hydrophobic fluoropolymer inner surface; but is not made of a porous material. As a result, this lens loop may not effectively function to prevent the isolation liquid, which may be of greater density than the aqueous reagent liquid, from sinking in whole or in part beneath the reagent liquid; nor does it effectively function to assure the presence of an isolation liquid layer of uniform and readily reproducible configuration atop the reagent liquid at all times attendant use of the dispenser with an automated sample liquid analysis system as described.
Each of U.S. Pat. Nos. 3,479,141, 4,121,466, 4,253,846 and 4,357,301 also discloses an automated sample liquid analysis system which makes use of an isolation liquid of the nature described hereinabove with regard to U.S. Pat. No. 4,515,753. None of these United States Patents discloses an isolation liquid retention device embodying the structure and function of the device of this invention.